Control system



Jan. 8, 1929. 1,698,560

J. B. PRICE CONTROL SYSTEM Filed Oct. .9, 1926 INVENTOR James BPrice.

M TORNEY Patented Jan. 8, 1929.

UNITED STATES JAMES B. PRICE, OF PITTSBURGH, PENNSYLVANIA.

CONTROL SYSTEM.

Application filed October 9, 1926. Serial No. 140,532.

My invention relates to control systemsfor alternating current motors, and more particularly to systems for the control of motors employed in load conveying and hoisting operations.

One object of my invention is to provide a simple and effective system for controlling a brake of an electromagnetic or other type employed in connection with motors of the above designated character.

Another object of my invention is to provide a means for holding the brake in its released position during the interruption of the circuit to the motor when anauto-starter is being actuated from the start-to the run position.

The single figure of the V accompanying drawing is a diagrammatic view of a control system embodying my invention, as applied to a squirrel-cage hoisting motor.

Referring to the drawing,a squirrel-cage motor 1 may be connected to a source of energy, embodying three-phase line conductors 2,

8, and 4, through a manually operated autostarter comprising transformer coils 5 and 6 and a multiple-pole, double-throw switch 7 that is assembled in a well-known manner and requires no further explanation.

An electromagnetic brake 8 is utilized in accordance with customary practice, being held in braking position by a spring 8a and bein released by the energization of a releasing coil 9, which may be connected to the source through a relay 10, a stop switch 11, an overload relay 12, and the doublet-brow switch 7 of the auto-starter. The releasing coil 9 is energized durin the interruption of the circuit to the motor w on themovable contact members of the starting switch 7 are moved out of engagement with the starting contact terminals 13, 14, 15, 16 and 17, and three of themare moved into engagement with the running contact terminals 18, 19, and 20, by reason of the relay 10 being held closed through a circuit that is established by interlock 21 that connects the actuating coil 22 0f the relay directly across the line conductors 2 and 8.

As arranged in this construction, my inventionoperates as follows: Assuming that the double-throw starter switch 7 has been thrown to the starting position, as illustrated, by means of the actuating handle 26, the motor will be energized at a suitably reduced voltage, inasmuch as the transformer coils 5 and 6 of the starter are connected to apply approximately one-half voltage to the motor windings through the illustrated intermediate taps, in accordance with familiar practice. The motor will thus begin to rotate, provided the electric brake 8 is released. The releasing coil 9 of the brake 8, being connected begized when the motor is started, and thereby cause the brake to be released.

The brake will be held released during the transition period when the switch 7 interrupts the circuitto the motor and while it is being moved from the starting to the running position, by reason of the circuit through the relay coil 22 being connected from line conductor 3, through the interlock 21 on the relay 10, the overload relay 12 and the stop switch 11, to line conductor 2. The releasing circuit will be maintained during the transition and after the starting switch 7 is thrown and until the circuit is interrupted by the stop switch 11 or by the circuit being opened by the overload relay 12, which is actuated by the overload coil 25, connected in series relation with one phase of the motor circuit. The circuit, be-

ing interrupted by either of these devices, the

releasing coil 9 is deenergiz'ed to permit the brake to be applied by the spring 8a.

One of the special features of my invention is thus the releasing of the brake during the operation of the motor-from the initial period of starting until it is de-energized.

It will be seen'that my invention may be readily adapted to mechanically, as well as manually, actuated auto-starters, and any brake may be utilized that is electrically controlled.

Having thus described an embodiment of my invention, I wish it to be understood that I do not desire to be limited to the particular construction or arrangement of parts herein illustrated, but that only such limitations shall be imposed as are indicated in the appended claims.

I claim as my invention:

1. A control system comprising an alternating-current motor, a plural-position autostarter and an electromagnetic brake therefor, said brake having a releasing coil, and

means responsive to the auto-starter for maintaining said releasing coil energized to release said brake duringoperation of said auto-starter from one position to another. I

- 2. A control system comprising an alternating-current motor, a plural-position autostarter and an electromagnetic brake therefor, said brake having a releasing coil, and means responsive to the auto-starter for maintaining said releasing coil energized to release said brake during operation of said auto-starter from the starting to the running position.

3. A control system comprising a squlrrelcage mot-or, an auto-starter and an electromagnetic brake therefor, said brake having a releasingcoil, and means responsive to the auto-starter for maintaining said releasing coil energized to release said brake during the entire operation of said motor by means of said auto-starter.

4. Acontrol system comprising a squirrelcage motor, a plural-position auto-starter, an electromagnetic brake for said motor, said brake having a releasing coil, and means responsive to the auto-starter for maintaining said releasing coil energized to release said brake during the operation of said autostarter from one position to another.

5. A control system comprising an alternating-current motor, a plural-position autostarter and an electromagnetic brake therefor, said brakehaving a releasing coil, and a relay provided with an interlock, said relay being so connected as to be actuable when said auto-starter occupies one position to complete a circuit to said releasing coil to release said brake, said interlock on said relay serving to hold said relay closed during actuation of said starter from one position to another.-

6. A control system comprising a squirrelcage motor, a plural-position auto-starter and an electromagnetic braketherefor, said brake having a releasing coil, a relay provided with an interlock, said relay'being so connected as to be actuable when said auto-starter occupies one position to complete'a circuit to said releasing coil to release said brake, said interlock on said relay serving to hold said relay closed during actuation of said starter from one position toanother;

magnetic brake therefor, said brake having a releasing coil, a relay provided with an interlock, said relay being so connected as to be actuable when said auto-starter occupies the starting position to complete a circuit to said releasing coil to release said brake, said interlock on the relay serving to hold the'relay closed during the entire operation of the motor by means of said auto-starter.

9. A control system comprising a squirrelcage motor, a transformer-tvne auto-starter, a multiple-pole double-throw switch and an electromagnetic brake for said motor, said brake having a releasing coil, a relay with an interlock, a stop switch and a source of energy, said auto-starter being connected between said motor and said source, said relay being connected to said double-throw switch tocause said releasing coil to be energized to release said brake when said double-throw switch is actuated to the starting position, and said interlock on said relay being adapted to hold said relay closed after starting and until the circuit is interrupted by said stop switch. V

10. A control system comprising in combination, a motor. a brake for the motor, an auto-starter for the motor, means responsive to the operation of the auto-starter for maintaining the brake in an inactive position from the time the motor is started until the supply of current to the motor is interrupted.

In testimony whereof, I have hereunto subscribed my name this 30th day of September JAMES B. PRICE. 

